What is com.google.android.apps.nbu.files.provider/2?

Question

I've opened pdf file from different sources and got this Intents:

File manager (Google Files) -> Internal storage -> Download: Intent { act=android.intent.action.VIEW dat=content://com.google.android.apps.nbu.files.provider/1/file:///storage/emulated/0/Download/Untitled.pdf typ=application/pdf flg=0x13000001 cmp=team.sls.testapp/.ActivityMain }
File manager (Google Files) -> Downloads: Intent { act=android.intent.action.VIEW dat=content://com.google.android.apps.nbu.files.provider/2/1863 typ=application/pdf flg=0x13000001 cmp=team.sls.testapp/.ActivityMain }
Dowdload manager (from notification panel): Intent { act=android.intent.action.VIEW dat=content://com.android.providers.downloads.documents/document/1508 typ=application/pdf flg=0x13000003 cmp=team.sls.testapp/.ActivityMain }
Telegram chat: Intent { act=android.intent.action.VIEW dat=content://org.telegram.messenger.provider/media/Telegram/Telegram Documents/2_5276292126848585208.pdf typ=application/pdf flg=0x13000001 cmp=team.sls.testapp/.ActivityMain }

What is content://com.google.android.apps.nbu.files.provider/2/1863 and why the path to same file is different? But more interesting - why cases 1 and 4 can open files with custom extensions but 2 and 3 don't?

If there is a misunderstanding with cases 1 and 2, take a look to screenshots in this question

"But more interesting - why cases 1 and 4 can open files with custom extensions but 2 and 3 don't?" -- their `Uri` values do not have file extensions. This is one of the many reasons why custom file extensions have never worked well in Android. — CommonsWare, May 21 '21 at 14:17
@CommonsWare, so it isn't any way to open files with custom file extensions from everywhere? Mechanisms of standard mime-types for applications are not available to us? — badadin, May 21 '21 at 14:33
"so it isn't any way to open files with custom file extensions from everywhere?" -- correct. This is no different than the Web, where a URL does not need to have any particular file extension. "Mechanisms of standard mime-types for applications are not available to us?" -- common MIME types are fine. For example, all four of those would work fine if, instead of filtering on an extension, you filtered on the `application/pdf` MIME type. — CommonsWare, May 21 '21 at 14:36

score 0 · Answer 1 · answered Jun 28 '21 at 23:48

All these four Uri's are following the same pattern

content://com.google.android.apps.nbu.files.provider/1/file:///storage/emulated/0/Download/Untitled.pdf
content://com.google.android.apps.nbu.files.provider/2/1863
content://com.android.providers.downloads.documents/document/1508
content://org.telegram.messenger.provider/media/Telegram/Telegram Documents/2_5276292126848585208.pdf

content://PACKAGE_NAME.provider/CONTENT_DETAIL

Obviously the PACKAGE_NAME depends on application.
And the CONTENT_DETAIL is optional, either file_id or full_path.

If you decompile all these four applications and look at their AndroidManifest.xml you will see the same provider tag with minor differences.

Look at Google Files's AndroidManifest.xml

<application>
  <provider 
    android:name="com.google.android.libraries.storage.storagelib.FileProvider" 
    android:exported="false" 
    android:authorities="com.google.android.apps.nbu.files.provider" 
    android:grantUriPermissions="true"/>
</application>

This provider will generate the HierarchicalUri's like bellow content://com.google.android.apps.nbu.files.provider/1651/2

Using the snippet bellow, you can read file/content from all those four application's.

public final class MainActivity extends AppCompatActivity{

   @Override
    protected void onCreate(Bundle savedInstanceState) {
      Intent intent = getIntent();
      InputStream is = getContentResolver().openInputStream(intent.getData());
      String content = new String(Utils.unwrap(is));
      Log.i("TAG", "content: " + content);
   }

   public static byte[] unwrap(InputStream is) throws IOException {
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        int nRead;
        byte[] data = new byte[4096];
        while ((nRead = is.read(data, 0, data.length)) != -1) {
            baos.write(data, 0, nRead);
        }
        baos.flush();
        is.close();
        baos.close();
        return baos.toByteArray();
   }
}

I hope i have answered your question.

What is com.google.android.apps.nbu.files.provider/2?

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